In pulmonary arterial hypertension (PAH) an increased pulmonary vascular resistance results in chronic pressure overload on the right ventricle and induces pathological right ventricular (RV) remodelling and RV failure. This causes limited exercise capacity, fatigue and increased mortality. Several treatment options have become available for PAH, and in patients given monotherapy, a second drug of a different class is given to improve symptoms and exercise capacity. Whether the addition of a second treatment reverses RV remodelling has not been described. In this study, the phosphodiesterase 5 inhibitor sildenafil was added to treatment with bosentan, an endothelin receptor antagonist. The objective of this study was to investigate whether the addition of sildenafil reverses RV remodelling and further improves RV function in patients with PAH treated with bosentan.

METHODS

In 15 patients with PAH receiving bosentan for one year, sildenafil was added for three months. Sildenafil was started at 50 mg twice daily and increased to 50 mg thrice daily after four weeks. At the start of the study and again after one year of bosentan, right-heart catheterisation with vasoreactivity testing, cardiac magnetic resonance (CMR) and 6 min walk test (6MWT) were performed. N-terminal pro-brain natriuretic peptide (NT-proBNP) was determined after one year of bosentan and after three months of combination therapy. After three months of combination therapy, the effects of the addition of sildenafil were evaluated with …